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Since when did youtube ever support 4k video playback in safari? I was under the impression that I needed to run it in chrome on my desktop for that.

I think some of the first so many 4K videos uploaded to YouTube were (and still are) playable in 4K within Safari (I think they’re encoded in h264 which allowed this), but then shortly after 4K was only encoded in VP9 requiring chrome for 4K playback.

Actually, worse than iOS or macOS, Youtube on Apple TV not having 4K playback is a real bummer.
 
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